How does light house work?


I keep reading that lighthouses help sailors 1) be aware of dangers like rocks and reefs, and 2) navigate in the dark. I understand that lighthouses beam a series of flashes that a sailor can see from far away, but I’m not quite sure how seeing a series of flashes in the dark from a single point-source can accomplish point 1 and point 2.

In: 8

It’s an immediate warning to sailors that there is land nearby, so they should start minding their depth and location. Ideally, the sailors have maps/charts for the areas they are sailing in, so they can identify which lighthouse it is based on surrounding terrain (or rough estimate) and use that, along with their maps/charts, to find where the hazards are nearby.

So the lighthouse isn’t to tell the sailors anything except their location, with the sailors responsible to figure out the rest.

The flash pattern (and colour) identify which lighthouse it is. The ship has a map that shows where lighthouses physically are. The ship also has a compass so it knows what direction it’s pointed and what bearing the lighthouse is. With all that information, you can put a line on the chart through the lighthouse and your ship must be on that line.

If you know how fast the ship is moving (which you should) and you can measure how fast the lighthouse’s bearing is changing, you now also know (approximately) how far you are from the lighthouse. The closer you are, the faster the lighthouse’s bearing will change.

Combine all that, and you know where you are. And, crucially, you know where the lighthouse is, which is a place you don’t want to be because the lighthouse is built on top of something that you should not snuggle your ship up to.

lighthouse = shore = reefs, rocks and low water.

it’s like a amber flashing light in traffic. it tells you that there could be danger but not what it is.

With the aid of a map and compass, knowing where the lighthouse is helps pinpoint a location. It is simply a fixed reference point.

It doesn’t make it possible to navigate in the dark but with a precise location, it is much simpler to avoid known dangers like shallow waters or reefs (which are marked on maritime maps)

Well the first point is simple. You build the light house ON the dangerous rocks or reef (or right next to it. That way ships know to stay far away from the lighthouse to avoid getting shipwrecked.

And as for navigating in the dark, the majority of the time the ships captain and crew already knew the path they were planning on taken, and chances are had taken that path before. So the lighthouse just acted as a check point. You would keep track of where you thought you were on the map, and then when you were supposed to be passing a lighthouse check if you could see the lighthouse.

If you could see the lighthouse you knew you were on course, if you couldn’t see the lighthouse that meant soemthing was up, maybe the wind is blowing you off course, maybe you’re not moving as fast as you thought, etc etc.